Big Sister Sweetie Belle?
by SPB
Summary: (Originally published on FimFiction in 2013, one of my first fanfics. Takes place between Seasons 3 and 4, rated Teen to be safe.) Sweetie Belle accidentally turns Rarity into a foal as the result of a spell. Now Sweetie Belle's the big sister, and must care for her "little sister" until she can turn Rarity back to normal.


"Rarity, you promised me you were going to help me practice my magic." Sweetie Belle said crossly.

"Oh. Did I really say that?' Rarity asked, she was busy working on designs for a new dress. Business at Carousel Boutique had picked up recently, and Rarity had been swamped with orders.

"Yes you did." Sweetie Belle said "You said you'd teach me today."

"Oh I did didn't I?" Rarity replied. She was trying to rack her brain. remembering when exactly she had agreed to do that. After all she hadn't even been planning on Sweetie Belle staying over, but her parents had insisted. Despite trying her hardest she found that, somehow the memories of agreeing to help Sweetie Belle had slipped her mind.

"Come on Rarity." Sweetie Belle pleaded "Teach me."

Rarity looked at Sweetie Belle, then at her designs, then back at Sweetie Belle. Sweetie Belle had only recently started to show signs that she could use magic. And even then it had been limited to a few sparks. She had gotten a few lessons, courtesy of Twilight. And had even mastered a few basic spells, but she was still behind most unicorns her age in terms of magic.

"Please?" Sweetie Belle begged.

Rarity sighed, she knew that Sweetie Belle likely wasn't going to stop bugging her until agreed. She was just thankful that the design she was working on was for a client. Who, thankfully, wasn't expecting the dress for another week. " _Besides_ " Rarity thought " _What's the worst Sweetie Belle could do?_ "

"So are you going to teach me now?" Sweetie Belle asked.

"Yes." Rarity said.

"Yay!" Sweetie Belle cheered "Thank you so much Rarity!"

Rarity couldn't help but smile a little at Sweetie Belle's enthusiasm, she had to admit it warmed her heart to see her little sister so happy. Still she knew from experience that magic practice was hard, and she knew that it could be very frustrating.

"So what are we going to practice first?" Sweetie Belle asked.

Rarity racked her brain, trying to think of something that Sweetie Belle could practice. She already knew that Sweetie Belle had practiced some of the basics. And she knew Sweetie Belle was likely going to want to try something a little more difficult. But she wanted to make sure that, if that something went wrong, Sweetie Belle wouldn't damage, or even possible destroy the boutique. Suddenly, an idea came to her head. "Stay put Sweetie Belle." she instructed "I'll be right back." Rarity returned a few seconds later with a flower pot.

"So what do you want me to do?" Sweetie Belle asked.

"The flower in this pot has seen better days." Rarity explained "I want to see if you can potentially restore it to the way it use to be."

"I guess I can try to do that." Sweetie Belle said. She began to try and light up her horn.

Rarity meanwhile, realized that she might have been asking too much of Sweetie Belle, considering how Twilight had trouble with age spells until she became an alicorn. Chances were that Sweetie Belle was going to run into trouble as well. Still, this could serve as an opportunity to see how strong Sweetie Belle's magic was, and then she could go from there.

Sweetie Belle found it hard to get her magic going. It seemed like all she could do was produce a few light green sparks from her horn.

Rarity took notice of the worry on Sweetie Belle's face, and tried to offer her some encouragement. "You can do it Sweetie Belle." she said "Just try to focus. Look deep inside yourself. Find that little spark, and let it flow through you."

Following Rarity's advice Sweetie Belle shut her eyes, and tried to concentrate. She tried to remember the pointers that Twilight had given her. Suddenly Sweetie Belle felt her horn light up as a light green aura appeared around it. "I-I'm doing it, I'm doing it!" she said proudly. She got so excited that she started getting careless, and began shooting off beams of magic in all directions. Not even thinking about what could happen.

"Sweetie Belle, calm down!" Rarity said "Magic is a very powerful force, if you're not careful you could lose control of it!"

"Sorry sis." Sweetie Belle said. She tried to tone her enthusiasm down a little, but she found this hard to do. She attempted to focus on the flower and tried to surround it with her aura. Then suddenly, without warning, she shot off another beam. This one somehow bounced off of the flower pot.

Before Rarity had a chance to react the beam struck her head on. She disappeared in a puff of light green smoke before she could say anything.

As Sweetie Belle waited for the smoke to clear she began to grow worried. "Rarity?" she called out. There was no reply. Sweetie Belle called out again "Rarity? Are you okay?" Again there was no reply. Just as Sweetie Belle was about to call out a third time the smoke cleared, only to reveal that Rarity wasn't standing where Sweetie Belle had last seen her. Sweetie Belle started to panic. "Rarity? Rarity where are you?! Say something!"

"I'm right here Sweetie Belle." Rarity called out, her voice somehow sounding higher than usual.

Sweetie Belle looked down a bit from where Rarity had been standing. To her relief she saw that Rarity was unharmed. But something was different about her. "Um oops?" Sweetie Belle said nervously.

"Sweetie Belle!" Rarity said in a high pitched voice "What in the name of Celestia did you do to me?!" she recoiled at the sound "Is that my voice?" she asked herself.

"Um... well, you... see, the thing is..." Sweetie Belle said, she really wasn't sure how to explain this to Rarity.

"What did you do, what **DID** you do?!" Rarity demanded.

"How do I put this lightly?" Sweetie Belle said nervously. Then she got an idea. "Look in the mirror." she said.

Rarity turned to the nearby mirror, which she occasionally used when designing dresses to see how they'd look on an actual pony. What she saw made her shriek in horror. Looking back at her was a chubby little foal with bright blue eyes. There was no way it was possible. She looked in the mirror again, just to be sure that she wasn't seeing things. It was just as she feared after her first look, Sweetie Belle had somehow regressed her body to that of a foal's. It took her a while to recover from the shock. "Sweetie Belle! I demand that you turn me back to normal this instant!" Rarity demanded.

"I'm afraid I can't do that sis." Sweetie Belle said.

"What do you mean you can't?" Rarity asked "Change me back right now!"

"I don't know what I cast that caused all of this. Otherwise I'd have changed you back by now." Sweetie Belle explained.

"Well this is just great." Rarity said "I can't possibly be a foal. Not when I have so many dresses to work on, and so many things to tend to."

"Well whether you want to or not you're gonna have to be a foal again." Sweetie Belle said "At least until I can figure out a way to turn you back to normal. But don't worry. We're gonna have so much fun 'little sister'."

"What did I ever do to deserve this?" Rarity muttered under her breath.

"What did you say sis?" Sweetie Belle asked.

"Nothing." Rarity said "By the way, how is it possible that you can understand what I'm saying? I'm probably not even older than the Cake Twins now."

"I don't know, it's probably something to do with the spell." Sweetie Belle said "Now then, 'little sister', what should we do first?"

Rarity sighed "Well, as much as it pains me to say this, I'm going to need to wear a diaper now." she said "After all I **AM** a foal."

"But I don't think we have any diapers here." Sweetie Belle "And we can't go out and buy some, unless you like being publicly humiliated."

"You're joking right?" Rarity said "Anyway, I have a few diapers stashed in a special drawer in my room. They're from when Pinkie Pie brought the Cake Twins over while Sugarcube Corner was being renovated. And I'm hopeful that they'll fit me."

"You and me both." Sweetie Belle said as she carried her "little sister" upstairs. Having been to Carousel Boutique multiple times she knew where Rarity's room was. After a bit of searching she found the drawer Rarity had mentioned. Sure enough there was a stash of unused diapers. Along with, surprisingly, a bottle of foal powder. "Guess you wanted to be prepared huh sis?" Sweetie Belle asked.

"Well the whole foalsitting experience with the Cake Twins really changed my outlook on foals." Rarity said "I figured I should be prepared in case Pinkie Pie decides to bring the twins over again. There was just something about them that awoke a dormant part of me."

"That makes sense I guess." Sweetie Belle said as she looked around, trying to find someplace that could serve as a makeshift changing table. Eventually she located a shelf that looked like it wasn't used very often. Wasting no time she carried Rarity over to it, then went back to the drawer to retrieve a diaper and the bottle of foal powder. "Okay, let's see if this diaper fits you." Sweetie Belle said.

"Don't forget to put some foal powder in the diaper." Rarity said "The last thing I need is a diaper rash."

"Oh right." Sweetie Belle said "Thanks for reminding me." She carefully unfolded the diaper, and shook the bottle of foal powder over it until she was certain that she had used enough, sneezing slightly. Slowly she slid the diaper underneath Rarity. The she stopped, as if unsure of what to do next.

"You need help don't you?" Rarity asked.

"Um, yes." Sweetie Belle said.

Rarity sighed "Just do what I tell you to do okay?" she said and proceeded to instruct Sweetie Belle on how to properly strap up the diaper. To her relief, as well as Sweetie Belle's, the diaper fit perfectly. She even felt tempted to wiggle around in them a little. They were actually quite comfy, and gave off a slight "crinkle" every time she moved.

"So how does it feel to be in diapers again?' Sweetie Belle asked teasingly.

"Well I admit it's not as bad as I thought it would be, but I'm certainly not going to enjoy being stuck in them." Rarity said.

Just then the doorbell rang. "Who could that be?" Sweetie Belle asked.

Rarity sweat dropped. She knew who it was. "It's Spike." she said "I'd forgotten that I promised him we'd go gem hunting today."

"And you want me to tell him to go away don't you?" Sweetie Belle asked.

"Yes." Rarity said "I don't care how rude it is to turn away a guest, there is no way I'm letting Spike see me like this."

"Why not?" Sweetie Belle asked "I'm sure he wouldn't care what you look like."

"Regardless of what he'll think of me I'm not letting him see me in a diaper." Rarity said "No way, no how."

"Well what do you want me to say to him?" Sweetie Belle asked.

"Anything to make him go away. Except of course the real reason why I can't come." Rarity said "I know it's wrong to lie to Spikey Wikey, but there are some things are worse than lying to one of your closest friends. My dignity in shambles is one of them."

"Well okay, but you're going to have to make it up to him somehow." Sweetie Belle said "Now stay put and let me handle this. Unless you change your mind, and decide to let Spike see you."

"Do I look like I'm going anywhere?" Rarity asked "I mean, I'm a foal for Celestia's sake."

"A foal that can talk normally." Sweetie Belle said "Besides you say stuff like that to me all the time, and now it's my turn." She didn't wait for Rarity to reply and simply went downstairs. She opened the front door, and was promptly greeted by Spike. "Hi Spike." she said.

"Hi Sweetie Belle." Spike said "Say, where's Rarity?"

"Oh, she's uh, in the bathroom." Sweetie Belle said, quickly thinking of an excuse.

"Well can you go talk to her or something?" Spike asked.

"She prefers to be left alone in there." Sweetie Belle said.

"Well I can wait until she comes out." Spike said.

"You might have to wait a long time." Sweetie Belle said "Rarity told me she was probably going to be in there for quite a while."

"I can wait until then." Spike said.

"Really?" Sweetie Belle asked.

"Sure." Spike said "There's nothing I look forward to more than spending time with Rarity. If I have to wait for her then I will."

Sweetie Belle sighed, Spike was incredibly persistent. She had to think of something to get Spike to go away. Eventually she decided to come up with a half truth. "Actually Spike, Rarity _can't_ go gem hunting with you today." she said.

"Why not?" Spike asked.

"Well, you see, um... this is kind of a uh... busy time for her." Sweetie Belle said nervously.

"Really?" Spike asked "I mean I know business has been picking up around here lately, but I didn't think Rarity was **THAT** busy."

"Uh... well she is." Sweetie Belle said "And she asked me to tell you so."

"Oh, I see." Spike said "Well, just let me know when she's available." He turned to leave.

"Wait a minute Spike!" Sweetie Belle called out.

"What is it?" Spike asked.

"Can you do me a favor?" Sweetie Belle asked.

"I guess." Spike said "What can I do for you?"

"When you go back to the library can you ask Twilight to search for books on age spells?" Sweetie Belle asked.

"Why?" Spike asked.

"Let's just say that there's been some sort of 'Magic Mishap'." Sweetie Belle said.

"Well, I'll see what I can do." Spike said, and he promptly left.

Sweetie Belle sighed with relief. She felt bad about lying to Spike, but she was hopeful that what she had asked him to do would help her solve this "magic mishap". She made her way back upstairs to Rarity's room. True to her word Rarity had not moved an inch.

"Is he gone?" Rarity asked.

"Yes." Sweetie Belle said "And I asked him to ask Twilight about books on age spells, so hopefully you won't be stuck as a foal for a really long time."

"You didn't tell him what happened to me, did you?" Rarity asked.

"Of course not." Sweetie Belle said "Come on, have a little faith in me sis."

"That's easier said than done." Rarity said "Especially when it comes to somepony like you. No offense."

"None taken." Sweetie Belle said "But if I were you I'd watch what you say. After all, you don't want to make your 'big sister' angry. And don't think I'm not aware of what happens to foals who misbehave."

"I'll keep that in mind." Rarity said. Just then her stomach let out a loud rumble. Both she and Sweetie Belle laughed a little at the sound.

"Sounds like somepony's hungry." Sweetie Belle said playfully.

"Well to be honest dress making takes a lot out of you." Rarity said.

"You're telling me." Sweetie Belle picking Rarity up and carrying her in her hooves "Come on 'little sister'. Let's see if we can find something for you to eat." Sweetie Belle left Rarity's room and headed downstairs.

Spike couldn't stop thinking about Sweetie Belle's request as he made his way back to the library. He knew that Sweetie Belle had recently started taking magic lessons, but she had struggled with only the basics. So why was it that she had asked him, to ask Twilight to find books on age spells? After all age spells were some of the most advanced feats of magic, and Twilight had struggled with them until becoming an alicorn. The more he thought about it the more confused he became. Especially since he was certain from the way Sweetie Belle was acting, that she wouldn't tell him what was going on.

" _Ah you're thinking too much, Spike._ " he thought to himself " _Sweetie Belle asked you to do a favor for her and you're not going to let her down._ "

"Spike? What are you doing back so soon?" Twilight asked "I thought you were going gem hunting with Rarity today."

"I was." Spike said "But Sweetie Belle told me that Rarity was busy."

"Well she has been getting more orders lately." Twilight said "After all, being a friend of Equestria's newest princess certainly attracts attention to yourself."

"I know, I know." Spike said "I'm just kind of bummed she had to call off gem hunting because of it."

"Don't worry Spike." Twilight said "Considering how many dresses Rarity has to make I'm sure it won't be long until she needs to go gem hunting. And if worse comes to worse we can always pay her a visit. Are you ready to get back to work?"

"Before we start Sweetie Belle asked me to do a favor for her." Spike said.

"What did she want you to do?" Twilight asked.

"She said she wanted me, to ask you, if you could find some books on age spells." Spike explained.

"What for?" Twilight asked.

"She didn't say really. She just said there'd been a 'Magic Mishap." Spike said "She was acting rather odd though."

The words "Magic Mishap" didn't quite raise any alarms in Twilight's head, but they certainly didn't just slip her mind. "Alright Spike." she said, lighting up her horn "Let's get looking."

"Ready when you are Twilight." Spike said.

Sweetie Belle looked in each of the kitchen cabinets where she knew food was kept. Knowing that most foods would be impossible for Rarity to eat Sweetie Belle pushed them aside, trying to find something that Rarity actually **could** eat. "Come on, there's gotta be something." she said to herself.

Rarity, meanwhile, was trying her best to ignore the rumbling sounds coming from her own stomach. She knew she was hungry, and she certainly didn't like being reminded of the fact. All it did was further remind her how long she had been waiting. She tried her best to patient. After all regardless of what she was like now she was still a lady, and a lady was always patient. But after what seemed like several minutes to her she finally said "Sweetie Belle? What is taking you so long?"

"Hey, it's not my fault if I can't find something that you can actually eat." Sweetie Belle said "And the more you bother me the longer it's going to take!" Suddenly she realized what she'd just said "Wow! I'm starting to sound just like you."

"I know. Freaky isn't it?" Rarity said.

"I was just about to say the same thing." Sweetie Belle said.

"I might have guessed." Rarity said.

"Aha! Here we go." Sweetie Belle said and pulled out a jar of applesauce. "I know this isn't very fancy, but it's the best I can do."

"Whatever, just hurry up and feed me." Rarity said "I'm getting tired of hearing my stomach rumble every five seconds."

"Well first things first." Sweetie Belle said "Since you **ARE** a foal, and foals can't feed themselves, I'm pretty sure you know what that means."

"Oh no, there is no way you're feeding me." Rarity protested "I'd rather starve then let that happen."

"Come on Rarity. Don't be so stubborn." Sweetie Belle said "You'll only make this worse for both of us."

"I don't care." Rarity said "I'm not letting you feed me, and you can't make me."

"Rarity, we can do this the easy way, or the hard way." Sweetie Belle warned "I don't want to have to resort to the hard way, and I know you don't want me to either. So please co-operate."

"The answer is no." Rarity said "I will never let you feed me, regardless of whether or not my stomach keeps rumbling."

Sweetie Belle sighed, she really hadn't wanted for it to come to this. "Very well." she said somewhat reluctantly "You leave me no other choice."

"Do your worst Sweetie Belle." Rarity said "Nothing you say or do is going to convince me to let you feed me."

"You think so huh?" Sweetie Belle said "Well we'll just see about that." Sighing again she unscrewed the lid on the jar, and dipped a spoon into it. When she brought it back out Rarity closed her mouth, just as planned. Reluctantly, using her hoof, she pinched Rarity's nose shut. "You're gonna have to open your mouth if you want to breath." she said, and waited. Within seconds Rarity opened her mouth, gasping for air. Seizing the opportunity Sweetie Belle shoved the spoon of applesauce into Rarity's mouth and removed her hoof from Rarity's nose, instructing Rarity to swallow.

Rarity did so. The taste of applesauce turned out to be quite pleasant.

"Now are you going to co-operate, or do I have to do that to you again?" Sweetie Belle asked.

Rarity sighed "Okay, you win. You can feed me." she said "Just don't ever do that again."

"Hopefully I won't have to." Sweetie Belle said "Now open for the aeroplane."

Rarity said nothing, and let Sweetie Belle feed her spoonful after spoonful of applesauce. Surprisingly, she found that the applesauce tasted just as good as the finest sandwich. She assumed it had something to do with how sensitive foal taste buds were although she couldn't be sure. She'd have to ask Pinkie Pie, or The Cakes, the next time she saw them. Sweetie Belle meanwhile, made gesture after gesture as she continued to feed Rarity. And surprisingly Rarity found that she actually enjoyed them.

"See, that wasn't so bad. Was it sis?" Sweetie Belle asked, cleaning Rarity's face with a rag.

"I guess it wasn't." Rarity said "And I apologize for being so feisty earlier. That was very unladylike of me."

"I wouldn't say that Rarity." Sweetie Belle said "After all your body might be a little foal, but your mind is still a fully grown mare. I can't imagine what that must be like."

"Indeed you can't." Rarity said as Sweetie Belle picked her up. "I wonder how Twilight and Spike are doing with their 'research'?"

"Any luck so far?" Spike asked.

"Well, I've managed to find a few different books on age spells." Twilight explained "The problem now is that I don't know where to begin searching. Does Sweetie Belle want to know how to cast age spells, or how to undo them? Did the spell affect an inanimate object, or an animate object?"

"Perhaps I could ask her again." Spike said "Maybe I can get some answers."

"Actually, I have a better idea." Twilight said "Do you think you can try to use your magic to send a letter to Sweetie Belle?"

"Maybe." Spike said "Though what should I write just in case the letter goes to Princess Celestia?"

Twilight thought for a moment, trying to think of an answer. Then an idea came to her. "Okay Spike, here's what I want to you write."

Intending to have some "fun" with Rarity Sweetie Belle brought out a few toys. They were mostly just old toys that Sweetie Belle never played with anymore, but for some reason were always lying around.

"Sweetie Belle, do you honestly think I'm going to be interested in playing with your old toys?" Rarity asked "Even when I was your age I was never into these things."

"Don't tell me you've never played with toys before." Sweetie Belle said.

"I had my own toys that I played with as a filly." Rarity explained "But I'm not a filly now, am I?"

"Come on sis." Sweetie Belle said "You always get so wrapped up in your dress making that you barely even take time for yourself. Especially at this time of year."

"Running your own business is very hard work Sweetie Belle. If you were a little older you'd understand that." Rarity said.

"Well that may be, but don't you think you should be making the most of this?" Sweetie Belle asked "I mean chances are you're never going to get another opportunity like this. Just relax and enjoy yourself, maybe even unwind. I know I would."

"I would have plenty of time to unwind if you hadn't regressed me to a foal." Rarity said "You're actually lucky that I've gotten ahead in my work. Otherwise you'd be in big trouble."

"You can't always be thinking like that Rarity." Sweetie Belle said "Why do you think I constantly come over here after school, instead of heading straight home to Mom and Dad?"

"I always assumed you did it simply because it was less of a distance to walk." Rarity said.

"That's only half true." Sweetie Belle said "The main reason why I always love to come over here, is because I want to be able to spend time with you. Those moments that we do spend together always bring a smile to my face .And I know they do the same to you. And every time I come over here, I always hope that we'll be able to do more of them. But you're always so busy, and half the time you end up telling me to go home so you can work on your dresses."

"Sweetie Belle, you know that I cherish the time we spend together." Rarity said "Trust me when I say it isn't easy when I have to work on my dresses instead of being with you. But I do it so that we can afford to do so many wonderful things."

"I know that." Sweetie Belle said "But sometimes it seems like all you really care about are your dresses." She was trying to hold back tears. Rarity was shocked

"Sweetie Belle, I had no idea that you felt that way." Rarity said.

"Well I do." Sweetie Belle said "I know it's wrong of me to think so, but I just can't help it."

"It isn't entirely wrong to think that way Sweetie Belle." Rarity said "I suppose, maybe I have been focusing a little too much on my dresses lately. I promise that after this whole thing is over I'll do my best to spend more time with you."

"I'm glad to hear that." Sweetie Belle said. Suddenly there was a small purple swirl, and a scroll materialized on the floor.

"It must be from Spike." Rarity said.

"I know that." Sweetie Belle said "He was probably trying to get a hold of me." She proceeded to unfold the scroll and read it.

 _This is a test._

 _The intended receiver of this message is Sweetie Belle. If you are not Sweetie Belle please disregard this message._

 _If you are Sweetie Belle, please answer this question:_

 _Did you cast an age spell? And if so was it on an inanimate object or an animate object?_

"I never knew Spike could spend letters to ponies besides Princess Celestia." Sweetie Belle said.

"Neither did I." Rarity said.

"I'll send a reply right away." Sweetie Belle said.

"How do you plan on doing that?" Rarity asked.

"I'll see if I can use my magic to send it back to Spike." Sweetie Belle explained "I'm pretty sure I can do it, and if not I'll just mail it to Twilight." After instructing Rarity to stay put (and Rarity's reassurance that she wasn't going anywhere) Sweetie Belle left to retrieve a quill. A few seconds later she came back and wrote down a reply on another scroll. Now came the tricky part, she tried to light up her horn to see if she could send the original scroll, and her reply.

But even though she followed Rarity's instructions from earlier, she found that she didn't have enough magic to perform a spell that was powerful enough to affect the scrolls. "Guess that age spell took more out of me then I thought." she said, and carefully folded the scroll. She then went outside, placed it in the mail box, and put the flag up. Within seconds a mail pony came by and picked it up.

Just after Sweetie Belle came back inside Rarity started to get a familiar feeling. Within seconds she knew what it was, the applesauce on was on it's way out. She should've figured that something like this would happen eventually after eating that applesauce. Thankfully the feeling wasn't very strong, yet. But she had to bring this to Sweetie Belle's attention, and fast. "Um Sweetie Belle." she said, trying to stay calm.

"Yes Rarity?" Sweetie Belle asked.

Rarity froze, trying to figure out how to put what she wanted to say lightly, but still get the point across. After a moment of hesitation she said "I...um...have to...go."

"Go?" Sweetie Belle asked.

"You know... to the little fillies room." Rarity said.

"Oh, I see." Sweetie Belle said "Well just let me know when you need a change, okay? After all we don't want you to get a rash, now do we?"

"Sweetie Belle, didn't you hear what I just said?" Rarity said "I have to go to the bathroom, now!"

"Well that's why you're wearing a diaper." Sweetie Belle said "You are a foal after all."

"I don't care what I am." Rarity said "I may have let you feed me, but there is certainly no way I'm going to use my diaper. Not in a million years. And don't you dare think of tickling me, or forcing me to go."

"But foals your age aren't old enough to use the potty." Sweetie Belle said "You should've known that. I mean you said it yourself, you're probably not even older than the Cake Twins and they aren't potty trained yet."

"Well I beg to differ." Rarity said "I demand that you remove my diaper and let me use the bathroom this instant!" She proceeded to try and use her magic only to find that all she could do was produce a few sparks. She then tried to use her hooves to undo the straps on her diaper, but that didn't work either.

"How do you even plan on going?" Sweetie Belle asked "The seat's way too big for you. And I'm not going to help you."

"I'll think of something." Rarity said, already trying to rack her brain for an idea.

"Even if you could make it up there you won't be able to balance yourself. You'd slip right off." Sweetie Belle teased

"You don't know that." Rarity said, though in her mind she knew Sweetie Belle was probably right. But that didn't stop her from thinking of some way to use the porcelain throne.

"I'm sorry Rarity, but the answer is no." Sweetie Belle said "I know you're not going to enjoy it. But you should've known that this would happen when you said you were going to have to wear a diaper."

"I was hoping that a solution could be found before it would come to this." Rarity said, by now the urge to go was really strong. She wasn't sure how much longer she could resist it.

"I was hoping for that too Rarity." Sweetie Belle said "But like it or not we're just going to have to deal with this situation. I know it's not going to be pleasant, but there's nothing we can do about that."

"Sweetie Belle! You'd better take off my diaper right now! or so help me, when I get back to my normal self I'll" Rarity stopped mid sentence. She no longer felt the urge to go, and she could feel, as well as smell, that her diaper needed to be changed. She tried to hold back tears. Trying to resist the urge to press the back of her diaper to confirm the feeling.

Sweetie Belle plugged her nose, the smell was horrible. It smelled like rotten eggs, only ten times worse. Taking a deep breath she scooped Rarity up and said "Come on 'little sister'. Let's get you changed before you get a rash." She carried Rarity upstairs and into her room where the makeshift changing table was. Sweetie Belle carefully placed Rarity on it, doing her best not to make things even worse.

Rarity, meanwhile, was actually starting to cry. She really tried not to, but somehow she found that she couldn't stop herself from doing so.

Sweetie Belle did her best to not let the crying bug her, as she retrieved a fresh diaper, some wipes, and the bottle of foal powder. She brought the items over to Rarity who was still crying. "Don't cry sis." Sweetie Belle said "Soon you'll have a nice clean diaper."

Rarity stopped crying. "Do you even know what you're doing?" she asked.

"Well actually no." Sweetie Belle said "But diaper changing can't be that hard, can it?"

Rarity wanted so badly to facehoof at that moment. Instead she merely sighed "Looks like I'm going to have to walk you through this as well." Rarity said. "First things first, you're going to have to remove that dirty diaper."

"That shouldn't be a problem." Sweetie Belle said "I just do the opposite of what I did to strap it up right?"

"Yes." Rarity said "Just be careful when throwing that thing away. I don't want to have another mess to clean up."

"Geez Rarity! You act as if though I'm going to be handling a live bomb or something." Sweetie Belle said "Actually, now that I think about it, that's probably how you acted whenever you changed my diapers when I was a foal." She couldn't help but chuckle at the thought of Rarity making a big scene over a dirty diaper. Acting as if though it were the end of the world. She continued chuckling to herself as she threw the diaper into the trash. Recoiling slightly at the smell. "Didn't know you had it in you Rarity. You just about destroyed this one." she teased. Rarity didn't take kindly to that.

"Now make sure to wipe me down good." Rarity said "I want my coat to look spotless again."

"How do I do that?" Sweetie Belle asked.

"Just go back and forth until all signs of my" Rarity cleared her throat "'Accident' are gone."

"Can do." Sweetie Belle said. She went back and forth as many times as she felt was necessary. "Can you please hold still sis?" she asked at one point.

"Sweetie Belle, do you even know what these wipes feel like against my flank?" Rarity asked "They're so cold."

"Well the more you wiggle the longer this is gonna take." Sweetie Belle said, and continued to wipe Rarity's behind until she was certain the job was complete.

"Now I just sprinkle some powder into the new diaper and strap it up, right?" Sweetie Belle asked.

"Correct." Rarity said "Make sure there's a good amount in there. You know as I well as I do that I don't want to get a rash."

"Relax sis" Sweetie Belle said "I'll just sprinkle the same amount into this diaper as I did the previous one." And she did. She then proceeded to strap it up. "Now I guess I should wash my hooves." Sweetie Belle said.

"Obviously." Rarity said "Make sure to use plenty of soap and water. And scrub those hooves until you've finished saying the alphabet."

"Okay." Sweetie Belle said. She had to admit that being the big sister for a change was quite interesting. At times it had been fun, and at others time it had been quite challenging. Now she could see, to some extent, why Rarity always seemed to be under a lot of stress whenever she was around.

"Twilight, it worked!" Spike said.

"How do you know?" Twilight asked.

"I just got her reply in the mail." Spike said, holding up a scroll.

"Well, let's see what she wrote." Twilight said.

Spike proceeded to read the message.

 _Hey there, it's me Sweetie Belle._

 _I got the message._

 _I cast an age spell, and it was on an animate object. I hope that helps._

 _I don't know what I cast though, so I don't know how to undo it._

 _Please tell me what to do._

"Well that certainly narrows things down." Twilight said, as she searched through the first book under _How To Undo An Age Spell Cast On An Animate Object_. "Aha! Here we go!" Twilight proclaimed a few seconds later. "It says here that to undo any sort of age spell on an animate object, simply cast the opposite age spell, to reverse the effects."

"So I take it that means, if whoever was affected by that spell was regressed, all you have to do cast a spell that ages the object until whoever it is turns back to normal. Right?" Spike asked.

"Uh-huh." Twilight said "Hm, it also says here that the spell works best if the target is in a position where it is not very likely to move."

"So what do we do now?" Spike asked.

"Mail a response to Sweetie Belle, and tell her to make sure that whatever she's cast the spell on is in a state where it's probably not going to move." Twilight instructed "I'm going to go over there myself and cast the counter spell."

"Couldn't you just teleport?" Spike asked "I mean, it would save you a lot of trouble."

"I could." Twilight said "But it's been awhile since I used my wings, and I could use the exercise."

"Well if you're sure that's what you want to do." Spike said and proceeded to write another letter to Sweetie Belle.

Sweetie Belle had just finished giving Rarity a bath, much to Rarity's protests when she got the message. "Good news 'little sister'." Sweetie Belle said "Twilight's on her way over here as we speak."

"That means she can turn me back to normal right?" Rarity asked.

"Hopefully yes." Sweetie Belle said "But there is a catch."

"And the catch is?" Rarity asked, unsure of whether she wanted to know what it was.

"According to this scroll, you need to be in a position where you're probably not going to move." Sweetie Belle said "So I think everything will be better if you're asleep when Twilight comes over."

"But I'm not tired." Rarity said.

"Well maybe there's a way we can fix that." Sweetie Belle said, as she finished drying Rarity off.

"What are you going to do?" Rarity asked, afraid of what the answer might be.

"You'll see." Sweetie Belle said as she scooped Rarity up in her hooves. She carried her into the kitchen, and set her down on the counter.

"What are you doing?" Rarity asked. Sweetie Belle didn't reply, she merely went over to the fridge and opened it. She shut it a few seconds later and carefully placed a carton of milk on the table. She then proceeded to rummage through the various cabinets and drawers. After a minute of searching something caught her eye. "What's this doing here?" she asked. She pulled the object out, it was an unused baby bottle.

"That must be from the Cakes Twins last visit." Rarity said "I must've forgotten about it."

"That's exactly what I was thinking." Sweetie Belle said.

"Please tell me you're not going to do what I think you're going to do." Rarity said.

"I figured a bottle of milk might make you feel sleepy. I know it does for me." Sweetie Belle said "And of course this unused baby bottle is just what I needed."

"You expect me to drink milk from a bottle?" Rarity asked.

"Well why not?" Sweetie Belle asked "I mean I already fed you, changed you, and gave you a bath. Don't tell me you're going to protest this as well."

"I was going to, but considering I'm probably not going to be a foal for much longer, I suppose it wouldn't hurt." Rarity said.

"Good." Sweetie Belle said "Just give me a minute to heat it up, okay?"

"Okay." Rarity said. She didn't want to admit it, especially not to Sweetie Belle but a bottle of milk was surprisingly starting to sound nice right about now. She wasn't really sure why that was though.

A moment later there was a ding, and Sweetie Belle took the bottle out of the microwave. She gave it to Rarity, who drank it down without a moment's hesitation. Somehow much like the applesauce it tasted really sweet and she was almost tempted to ask for more. Sweetie Belle then picked her up, and burped her. "Feeling sleepy yet sis?" Sweetie Belle asked.

"No, not yet." Rarity said.

"Well hopefully that'll change soon." Sweetie Belle said and carried Rarity upstairs. She stopped in Rarity's room and carefully lowered Rarity onto the bed. "Are you starting to feel tired?" Sweetie Belle asked as she unmade the covers, and carefully tucked Rarity in.

"A little bit." Rarity said, letting out a yawn. The warm milk had worked like a charm.

"Want me to sing you a lullaby?" Sweetie Belle asked.

Rarity yawned again. "A lullaby does sound good." she said, holding back a yawn. She didn't want to mention to Sweetie Belle that she was already starting to nod off.

"Got any preferences?" Sweetie Belle asked.

"Just sing whatever you want Sweetie Belle." Rarity said.

Sweetie Belle sang the first song that popped into her head.

 _Hush now, quiet now_

 _It's time to lay your sleepy head_

 _Hush now, quiet now_

 _It's time to go to bed_

 _Drifting off to sleep_

 _The exciting day behind you_

 _Drifting off to sleep_

 _Let the door of dreamland find you_

 _Hush now, quiet now_

 _It's time to lay your sleepy head_

 _Hush now, quiet now_

 _It's time to go to bed_

Sweetie Belle looked at Rarity, and saw that she was fast asleep. She looked so peaceful and relaxed. Sweetie Belle had to admit it was hard to not think that Rarity looked so adorable. Too bad it would all have to end soon.

Just then the doorbell rang. Sweetie Belle was pretty sure she knew who it was. Wasting no time, she made her way downstairs and opened the door. Sure enough there was Twilight. "Hey Sweetie Belle." she said "Sorry I didn't just teleport here, but I figured a good flight would do my wings some good."

"That's alright Twilight." Sweetie Belle said "I'm just glad you came."

"So where's the object you cast the spell on?" Twilight asked.

"Follow me." Sweetie Belle whispered "And please keep your voice down."

Twilight was tempted to ask why, but said nothing as Sweetie Belle lead her upstairs, and into Rarity's room. Upon entering she saw why Sweetie Belle had asked her to be quiet. She saw Rarity sleeping peacefully in her bed. From a distance she could see that Rarity looked different, and it only took a second for her to put two and two together. "You cast the age spell on Rarity?" Twilight asked Sweetie Belle.

"Yes." Sweetie Belle said.

Twilight couldn't help but chuckle a little at the thought of what Rarity must've been like.

"You can make her normal again, right?" Sweetie Belle asked.

"Of course." Twilight said and promptly lit up her horn. Within seconds her horn glowed with it's familiar violet red aura. Wasting no time Twilight fired a beam at Rarity. There was a puff of violet red smoke, and when it had cleared Rarity was back to her usual self.

"Thanks for your help Twilight." Sweetie Belle said "I don't want to think what might've happened if you and Spike hadn't found the counterspell."

"Well just make sure this doesn't happen again, understand?" Twilight said.

"I understand perfectly. Don't worry I'll make sure that it never happens." Sweetie Belle said.

"Well then, if you'll excuse me I must be going." Twilight said "I've got lots of important things to tend to." and she disappeared in a flash of violet red light.

Rarity woke up a moment later. "Thank Celestia I'm back to normal!" she said happily "Now I can get back to working on my dresses."

"Don't forget about me Rarity." Sweetie Belle said.

"Sweetie Belle, I promise you that I'll spend all day tomorrow with you." Rarity said "And just for the record, don't ever cast another age spell on me. No matter what."

"Don't worry sis." Sweetie Belle said "Age spells are pretty hard to pull off. I doubt I'll ever be able to perform another any time soon."

"Good." Rarity said "And let's keep what happened today between the two of us okay?"

"Whatever you say, 'little sister'." Sweetie Belle said, chuckling.

When Rarity saw the absorbent undergarment still strapped to her, she laughed too. But it was a good, hearty laugh.


End file.
